Self coring grommet



p 1959 H. KOEHL 2,901,800 v SELF coRmc GROMMET Filed Sept. 10, 195-3 Fig.5

" Minn-m9" wfima 8 INVENTOR.

H E R MAN KO E H L HIS AT NEYS v 2,901,800 SELF CORING GROMMET Herman Koehl, Danielson, Conm, assignor to C. E. M. Company, Dayville, Conn., a partnership Application September 10, 1953, Serial No. 379,403

2 Claims. (Cl. 24-141) The present invention relates to a grommet unit employing a pair of telescoping gripping members commonly denoted rivets and eyelets. More particularly, the invention relates to a grommet unit employing a rivet or clamp member and a self-coring eyelet member.

It has long been a well-known expedient in the metal fastener field to provide various types of grommet units employing tubular telescoping members having flanges so constructed as to interlock when in telescoped position into a suitable sheet material to provide a reinforcement about a hole in such material. It also has been a common practice to provide one or the other of such telescoping members with serrated teeth for the purpose of piercing and gripping the sheet material and clamping the same tightly in cooperation with the other telescoping member. Alternatively, other forms of grommet units have relied upon a snubbing action between two telescoped flange bearing tubular members.

Up to the present invention, however, all prior art eyelet and grommet setting processes have involved an independent and separate material cutting or coring step in order to produce the hole in such material around which the eyelet or grommet serves as a reinforcement. Particularly, it has long been common practice to provide separate cutting and punching dies for punching holes through various types of sheet material prior to inserting and locking grommet and eyelet clamping members about such pierced hole. Such dies, however, are expensive and difficult to make and have relatively short, useful lives due to wear. As a result, the proper dimensioning of the hole with respect to the eyelet or grommet used has not been uniformly obtainable after short periods of operation of the punching dies.

Further, substantially all commercially available grommets or eyelets comprise a structure requiring an independent riveting or flange rolling operation. As a consequence, their use has been relegated to mass production operations in clothing factories and the like, in which special automatic machines and presses are provided. This practice still obtains even though special, manually manipulative die members and material perforating punches have long been provided for use by the housewife and seamstress. The expense and complexity of the punch and die members, together with the need for dexterity, has effectively prevented any extensive use of the grommet type reinforcements by these groups.

It is therefore a primary purpose of the present invention to provide a grommet unit which can be applied to various type materials without requiring specially designed tools or machines. Another purpose of the present invention is to make grommet units which can be applied to various materials in a simple, short-length operation to provide reinforced perforations therein by a single manipulative act. Yet another purpose of the present invention is to provide a simple grommet unit for use with various types of sheet material, such as cloth, leather, plastics, rubber, etc., and which employs Patented Sept. 1, 1959 2 an inherent structural feature for simultaneously coring the desired hole through the sheet material during the grommet or eyelet setting operation.

A particular unique feature of the present invention is the provision of an eyelet member which can be used interchangeably in a non-clinching, material snubbing fashion in cooperation with a second tubular grommet member, and alternatively, in a self-clinching, clamping operation in which the eyelet becomes imbedded in the matrix of the sheet material about the perforated, cored hole.

Accordingly, one object of the invention is to provide a unique two-part snubbing grommet. A further object of the invention is to provide a unitary self-coring and self-clamping eyelet. Another object of the invention is to provide a universal eyelet member which may be used in connection with sheet material, with or without a cooperating rivet or clamping member. (Ether and distinct objects will become apparent from the description and claims which follow.

Having broadly described the invention, reference will now be made to the accompanying drawings disclosing the specific embodiments thereof, and in which:

Fig. 1 is a schematic view, partly in section, of the eyelet member forming one part of the grommet unit of the present invention;

Fig. 2 is a schematic view, partly in section, of the rivet or clamping member forming the other part of the grommet unit of the invention;

Figs. 3 and 4 are schematic views illustrating the operation of the clamping and eyelet members of Figs. 1 and 2 in cooperation with a sheet material desired to be perforated and reinforced; and

Fig. 5 is a schematic view of a modified form of the invention.

Reference will now be made to Figs. 1 to 4, inclusive, which illustrate a grommet unit according to the present invention, and which is adapted to be inserted in, perforate, core, and snub any desired sheet material in a continuous sequential step. As shown in Figs. 1 and 2, the grommet members comprise a pair of tubular members 1 (Fig. l) and 4 (Fig. 2) which are adapted to be telescoped together through an intervening sheet of material. The tubular member 1 constitutes an eyelet and includes an out-turned arcuate flange 1a at one end of a tubular hollow stem 1 with a plurality of axially extended serrated tooth-like projections 2 at the other end thereof. The projections 2 are separated, one from another, by intervening transverse end sections 3 of the hollow stem 1. Both the axially projecting teeth 2 and the transverse side wall portions 3 are, according to the present invention, drawn or otherwise shaped to present a sharp angular surface at the inner peripheral edge. The arrangement is such that teeth 2 and edge surfaces 3 form a knife-like periphery which is adapted to bear against and perforate sheet material when the eyelet member is forced against the materials surface in cooperation with member 4. This construction of the eyelet member permits it to function as a self-coring member.

According to the preferred form of the invention, the eyelet member is adapted to cooperate with a rivet or clamping member 4 (Fig. 2) which includes a hollow stem with an integral radially outwardly extending annular flange 6 at one end. Flange 6 has a down-turned edge with an ogee curvature 6a. The other leading edge of the rivet member 4 is formed perpendicular to the tubular stem so as to present an outer sharp edge 5 which assists the knife edge of eyelet 1 when the rivet is pressed up against sheet material. Member 4 is of smaller circumference and length than member 1 for a purpose hereinafter apparent.

It will thus be appreciated that the grommet unit comprises two tubular members forming a rivet and eyelet unit in which each member comprises a simple flange bering hollow stem structure. .It will furtherbe noted that the flange structures comprise simple cup-like'contours which may be easily formed by stamping operations on a singletubular stock-piece. Howeven-ifdesired, the cupped flange portions rnay be formed separately and soldered or swaged onto the hollow stems.

The cooperation of the tubular members in connection With the sheet material in which the eyelet is designed to be inserted will be more readily understood from reference to Figs. 3 and 4- of the drawing which illustrate sequential steps in the inserting of the eyelet into a suitable sheet material. As shown in Fig. 3, the eyelet member 1 is presented to one side of the sheet material, as for example, the underside, while the clamping member 4 is presented to the other-side, as for example, the upper side, with member 4 being arranged to telescope within-the confines of the tubular portion 1. if desired, eyelet 1 and clamping member 4 can be arranged to be carried by opposed die heads in a suitable clamping'or punching press, while the material '7 is arranged to be moved between the opposed die heads when in the raised or unclamped position. With such arrangement, eyelet 1 and clamping 4 may be simultaneously moved, one towards the other, to telescope member 4 within the confines of the axially extending teeth-like points 2 on member 1 as such teeth pierce the material 7 in the manner illustrated in Fig. 3. At this point it will be noted that the sharp leading-edge of rivet or clamping member 4 is set continuously about the free edge of the material 7 encompassed by the tubular eyelet 1 in such manner that further movement of member 4 towards member 1 will serve to drag or push material 7 over the knife-like edges of the transverse periphery 3 and the lower portion of tooth projections -2 to shear or cut the same from the main body of the sheet 7.

This sequence of operative steps will be more fully understood by reference to Fig. 4 illustrating the respective grommet members when the clamping part 4 has been fully pressed within the tubular eyelet 1, and in which position the cen rally cored portion 8 of sheet material 7 has been punched from without the eyelet by reason of the piercing or cutting action of knife edges 2 and 3 and the cooperative ejection action of the front edge 5 of member 4. It will further be noted that continued pressing or telescopin of members 1 and together serves to bend the tooth-like projections 2 back upon themselves by reason of the guiding contact of teeth 2 with the ogee curvature 6a of flange 6 on member 4, with result that the annular flange la on eyelet It will be drawn upwards toward the underside of cloth 7, and in combination with the external surface of flange 6 on member 4, will snub or clamp the edge of the cored or perforated sheet member 7 therebetween.

It will be understood that the terminal edge of flange 1a, instead of being directed in such manner as to move into flush surface contact with material 7, may be formed to have a comically flared downwardly directed end whereby flanges la and 6 may be tightly wedged together, one within the other. In such case the flange in will present a deeper, cup-like contour which may include a radially inwardly directed bulge near its terminal end for the purpose of serving as a detent to lock the flange 6 of member 4 in a permanent fixed union therewith.

It will further be noted that the longitudinal extent of the rivet member 4 is substantially less than that of the combined extent of the tubular stem portion and tooth projections 2 of eyelet 1, and in fact comprises only a slightly greater length than the distance between the lower edge of flange 1a and knife edge 3:: on eyelet 1. This permits the insertion of both members into any type sheet material to core and snub the same without requiring any operation other than a simple pressing together.

Due to this construction, it is possible to apply the present grommet unit to most materials in a manual operation without need of a pressing or stamping machine. In its simplest form, the invention can be practiced by grasping the telescoped rivet and eyelet members by the thumbs and forefingers whilepinching or squeezing them together through the interposed material. This mode of application is limited, for people of average strength, to relatively lightweight materials with: grommets of thin gauge.

Thicker gauge grommets, however, can be easily 'applied in substantially alltype materials through the simple expedient of forcing the telescoped members together in a conventional hand pliers, or by striking them together with a mallet or hammer. In the latter case, it is preferred that the rivet be supported on a'stationary platform while the blow is applied to the flanged'head of the eyelet. This facilitates the bending or rolling back of teeth 2 in flange 6.

It will be obvious that the grommet units may be formed'of any suitable material such as brass, iron, steel, copper, synthetic plastics, etc., and that the dimensions may be varied as desired. It is preferred, however, to regulate the number of eyelet teeth between three and eight dependent'on the diameter of the number. With a smaller number of teeth, it is easier to insert the member through the sheet material, but this convenience must be balanced against the necessary centering and guiding action provided the cooperating rivet member, which is betterwith a greater number of teeth.

"One additional advantage of the present grommet construticon is the obtaining of a knife-like cutting action from relatively blunt faced tubular members by simply shearing or otherwise forming the perpendicular wallsurfaces on the stem portions of the members to present a sharp peripheral edge. Obviously, one or the other, or both of the stem portions 3 and 5 can be formed to have a knife-like leading edge by beveling or chamfering the edge to a point. Further, the tooth projections 2 can be formed to have a progressively reduced thickness so as to present a stilleto-like cutting surface.

A particularly effective combination can be provided by charnfering the leading face 5 of rivet 4 to present a knife-edge on its inner periphery, and chamfering eyelet spaces 3 to present knife-edges on the inner periphery of stem 1. Apart from producing a clean shearing action, such construction precludes sticking or wedging of the cored sheet plug 8 in the open channel of stem 1 and provides a positive ejection action identical to that of the Fig. 2 construction.

One of the particular features of the present invention is'the obtaining of a snubbing and clamping action while simultaneously providing for the coring of the snubbed material from the central opening of the eyelet unit. A further advantage of the present invention is the construction of the eyelet and cooperating rivet or clamping member in such manner, that as desired, the eyelet members may be inserted in proper position in the sheet material prior to applying the telescoping member 4 in cooperative relation therewith. In such case the eyelet members may be inserted in the sheet material With the toothed portions 2 projecting through the material and serving to hold the eyelet member therein, While also serving as a guide for subsequently positioning and orienting a rivet member 4 during its cooperative movement therewith. This facilitates the use of the instant grommet unit with various and different type presses.

A particularly eflicacious form of grommet clamping action may be obtained by eliminating the ogee curvature of the terminal edge 6a of flange 6 on rivet or clamping member 4. In such case the flange 6 may merely comprise a cub-like down-turned edge in parallel relationship .to the central tubular portion 4. With this type of construction, cooperative clamping action between member 4 and eyelet 1 in the manner previously described will serve to cause the toothed portions 2 of member 1 to become bent back upon themselves, but with a much less change in direction than with flange 6a, by reason of the curved guiding action of the flange 6 and to re-pierce the said opposite side of the material 7 at a point spaced from the initial penetration. At the same time continued movement of flanges 6 and 1a towards each other will serve to snub and tightly clamp material 7 therebetween, with the leading down-turned edge of flange 6 being forced radially inwardly by reason of the curvature of the underside of flange In. It will thus be appreciated that a dual clamping function is obtained without requiring any additional structural components.

A modified form of the invention is illustrated in Fig. 5 of the drawing in which the eyelet members serves as the sole grommet or clamping component in cooperation with cored sheet material. In this form of the invention, the eyelet member is constructed identical to that of Fig. l, as previously described, and is provided with a cooperating rivet or clamping member 4b having the same tubular stem portion and sharp circular edge 5b, but with an arcuately curved, shallow short flange 6b. The arrangement is such that the clamping or rivet member 4b cooperates with eyelet 1 in the manner previously described with the exception that the shallow cup-like flange 6b merely serves to reverse the direction of tooth portion 2 to cause the same to become redirected back towards flange 1a of member 1 along a diagonal reentrant line to clinch the material 7 by repiercing it at a point removed from the initial penetration. After the turning operation is completed, the member 4b may be withdrawn from the clamping eyelet 1 to leave the eyelet imbedded in material 7. It will be understood that the blunt edge 5b on member 4b serves to punch the core portion 8 from sheet material 7, in a manner identical to that previously described, during the tum-back of tooth portions 2. The tubular stem 4b, in this form of the invention, may comprise a stationary die forming a part of a stamping press which is adapted to cooperate with a moveable opposed die member serving to bring the eyelet member towards it to imbed it in the material 7, prior to telescoping member 1 on member 4.

One of the particular advantages of any form of the present invention is the elimination of any need for a separate grommet turning or riveting action, which is common to all prior grommet inserting processes. According to the present invention, the only bending operation necessarily present is the out-turning of tooth members 2 by reason of contact with the cup-like flange portion on member 4. It will be readily understood that this action permits the utilization of far less powerful stamping presses than would be necessary to turn the full free edge of a non-toothed tubular wall section. It will further be understood that the short length of rivet 4 facilitates the telescoping of the grommet members without requiring a final bending or swaging of the leading end 5b.

As many apparently widely diiferent embodiments of this invention may be made without departing from the spirit and scope hereof, it is to be understood that the above invention is not limited, except as defined in the appended claims.

What is claimed is:

1. An article of manufacture comprising a grommet unit having a pair of tubular telescoping members, one of said members comprising a rivet structure having a tubular core and a radially outwardly extending, arcuate flange, said rivet member being of relatively short length, the other of said members comprising an eyelet having a tubular stem portion terminating at one end in a plurality of axially-directed, arcuately-spaced teeth, said teeth being separated by an edge wall portion of said tubular stem, said edge wall portion being constructed to form a knife edge, said stem portion terminating at its opposite end in a radially outwardly-extending arcuate flange, said flange having a substantially straight rim extending radially outward from the free edge thereof, and the tubular core of said rivet structure being constructed to telescope within the tubular stem portion of said eyelet and to be entirely embraced within said tubular stem portion while the arcuate flange of said rivet distortingly embraces the teeth of said eyelet.

2. An article of manufacture as set forth in claim 1 in which said eyelet has a relatively long length, and said flange of said rivet member includes a terminal end having an ogee curvature for cooperation with said teeth on said eyelet to cause said teeth to bend radially outwardly of said eyelet and become wedged within said flange to lock said rivet member and eyelet together.

References Cited in the file of this patent UNITED STATES PATENTS 5,779 Penfield Sept. 19, 1848 84,900 Norcross Dec. 15, 1868 304,249 Wilcox Aug. 26, 1884 395,478 Brass Ian. 1, 1889 496,357 Hall Apr. 25, 1893 626,722 Pusey Jan. 13, 1899 1,467,280 Warner Sept. 4, 1923 1,887,466 Puc Nov. 8, 1932 2,562,005 Wenzel et al. July 24, 1951 

